Which vs. That

By: Brian A. Klems | August 7, 2012

The battle over whether to use which or that is one many people struggle to get right. It’s a popular grammar question and most folks want a quick rule of thumb so they can get it right. 

Here it is.

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Q: I’ve been writing for a long time and always assumed which and that were interchangeable, but I’ve recently been told that isn’t the case. How do I make sure I’m using the right word? —Anonymous

The battle over whether to use which or that is one many people struggle to get right. It’s a popular grammar question and most folks want a quick rule of thumb so they can get it right.

Here it is:

If the sentence doesn’t need the clause that the word in question is connecting, use which. If it does, use that. (Pretty easy to remember, isn’t it?) Let me explain with a couple of examples.

Our office, which has two lunchrooms, is located in Cincinnati.
Our office that has two lunchrooms is located in Cincinnati.

These sentences are not the same. The first sentence tells us that you have just one office, and it’s located in Cincinnati. The clause which has two lunchrooms gives us additional information, but it doesn’t change the meaning of the sentence. Remove the clause and the location of our one office would still be clear: Our office is located in Cincinnati.

The second sentence suggests that we have multiple offices, but the office with two lunchrooms is located in Cincinnati. The phrase that has two lunchrooms is known as a restrictive clause because another part of the sentence (our office) depends on it. You can’t remove that clause without changing the meaning of the sentence.

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I know many of you get tired of hearing me say, "You suffer from the 'that' syndrome." You might also note the use of commas in the sentences above. They are often used to set off a restrictive clause.

In my writing, I suffer from the same malady. Too often 'that' simply jumps onto the page from my fingers without my brain being in gear. Proofing text is the only true way of finding the issue. If you use a word processer or computer, the program you employ probably allows you to search for the word you wish. Find 'that' and read the sentence. If it meets the criteria, leave it alone, if not change it to 'which'. Then do the same for 'which'.

I did this for my latest bit of work, some 50,000 words, and found 39 instances in which I erred.

Good Luck and Keep on Writing!